The Impact of Host Genotype, Intestinal Sites and Probiotics Supplementation on the Gut Microbiota Composition and Diversity in Sheep

SIMPLE SUMMARY: Given the fact that sheep serve as an increased meat product consumption in China, as well as a suitable model for fat deposition, their digestive tract microbiota has drawn growing attention. Our study depicted the gut microbiota community composition and diversity of sheep with varied genotypes but shared geography, with different sampling intestinal sites and probiotics supplementation time. The results indicated the great difference of the gut microbiota in samples from different sheep breeds, various intestinal sites, and different probiotics feeding times. Additionally, all results implied the dominance of the host factor in shaping unique microbiota under a certain environment, the greatest similarity of colonic and fecal microbiota, and the oral probiotic effectiveness for a given period of time for sheep. ABSTRACT: Three sampling strategies with a 16s rRNA high-throughput sequencing and gene expression assay (by RT-PCR) were designed, to better understand the host and probiotics effect on gut microbiota in sheep. Sampling: (1) colon contents and back-fat tissues from small-tailed Han sheep (SHS), big-tailed Hulun Buir sheep (BHBS), and short-tailed Steppe sheep (SHBS) (n = 12, 14, 12); (2) jejunum, cecum and colon contents, and feces from Tan sheep (TS, n = 6); (3) feces from TS at 4 time points (nonfeeding, 30 and 60 feeding days, and stop feeding 30 days) with probiotics supplementation (n = 7). The results indicated SHS had the highest Firmicutes abundance, the thinnest back-fat, and the lowest expression of C/EBPβ, C/EBPδ, ATGL, CFD, and SREBP1. Some bacteria orders and families could be potential biomarkers for sheep breeds with a distinct distribution of bacterial abundance, implying the host genotype is predominant in shaping unique microbiota under a shared environment. The microbiota diversity and Bifidobacterial populations significantly changed after 60 days of feeding but restored to its initial state, with mostly colonies, after 30 days ceased. The microbiota composition was greatly different between the small and large intestines, but somewhat different between the large intestine and feces; feces may be reliable for studying large intestinal microbiota in ruminants.